Spinal discs and/or other vertebral changes can cause spinal disease that often leads to patient discomfort or even paralysis. For example, intervertebral spinal discs, which lie between adjacent vertebrae, can break down or degenerate, resulting in disc fluid loss and consequently resulting in a loss of disc flexibility. In addition, discs can become thinner, allowing the vertebrae to move closer together, may tear or crack in the outer layer and/or the annulus of the disc, and/or bulge outwardly. Facet joint degeneration may also lead to spinal disease. Physical trauma (e.g., accidents, injuries, strains, etc.) may cause spinal column changes, and spinal stenosis can cause the spinal canal to narrow due to excessive bone growth and/or thickening of tissue. In all of these conditions, the spinal canal through which the spinal cord and the spinal nerve roots pass may become narrowed, creating pressure on nerve tissue. Such pressure can cause pain, numbness, weakness, or even paralysis in various parts of the body.
Some methods for treating spinal diseases, such as those described above, limit the movement of adjacent vertebrae relative to one another to limit the additional pressure on the local nerve tissue by maintaining a minimum disc space and/or space surrounding the adjacent vertebrae. Various methods have been performed to maintain this minimum space, including disc implants and spinal fusions. One method includes implanting a spacer between two adjacent posteriorly extending spinous processes, which in effect maintains a maximum space between the corresponding vertebrae. Some existing spacer implant devices are implanted by affixing the device to adjacent spinous processes. Existing spacer implants, however, do not provide complete access to insert bone growth promoting substances into the spacer after implant. In addition, existing spacer implants do not provide structural integrity between two adjacently implanted spacers. Moreover, the procedures required to implant existing spacer implant devices are overly complicated, requiring the use of multiple tools to position, tighten, and secure the implants to the spinous processes.
Therefore, there remains a need for improved interspinous process spacer implants.